This 64-year-old man underwent implantation of an Adapta dual chamber pacemaker; he suffered from paroxysmal episodes of AF with rapid ventricular response accurately diagnosed by the device; upon arrival for a routine follow-up visit, the pacemaker is in DDIR fallback mode with a rapid spontaneous ventricular rhythm; the device was programmed during the visit to the conducted AF response algorithm and the tracing was recorded.
The first channel is lead I of the surface ECG with the event markers superimposed, the second shows the atrial EGM and the third channel shows the time intervals;
In patients presenting with AF and rapid AV conduction, the rhythm irregularity may be the cause of disabling symptoms and a fall in cardiac output. The principal aim of the response to conducted AF algorithm is to eliminate long diastolic intervals. The algorithm operates only during mode switches. The increase in pacing rate caused by the response to conducted AF algorithm is limited by the programmed upper rate. Rapid ventricular pacing might also decrease the spontaneous mean ventricular rate by the phenomenon of concealed retrograde conduction.
This type of algorithm has some limitations. Its ability to control symptoms in a large population seems uncertain. In addition, this forced pacing is energy consuming.
